By the way, does anyone play difficulties 9 to 10 with realistic map type? I always play realistic and have not yet cracked diff 8, not that I'm all that good at the game.
I play simple-hubs on difficulty 9, realistic just looks too messy and if you use a custom galaxy layout everytime you load the game you have to back and load your galaxy layout again, gets a bit annoying.
For a new player i would say 300-400 Ai progress at 6/7 is fine. Once you've got a win or two under your belt then try to get that AI progress lower.
I would actually use a MK II nuke if the AI progress wasn't so high, better just to use singles. Though nuking a hub with 18 connections with a MK II.... Always fun. MK III though... i would attempt it but you can't build anything anymore because of no energy, now if there was a way around this apart from having lots of starships pre-built.